双层板桁钢梁应力分析

Stress Analysis for Double-deck Steel Trussed Girders

以跨度最大的双层斜拉桥闵浦大桥为背景,研究了双层板桁钢梁桥面板的受力特性,阐述了精细壳单元与梁单元结合的整体有限元模型,并分析了上、下桥面间腹杆的受力特性与桥面板的应力分布特性;采用桥面纵横梁间带U肋精细桥面模型,分析了桥面板和U肋在车辆荷载作用下的应力分布。研究表明,上、下层桥面横桥向应力小于纵桥向应力,并且横桥向应力的不均匀性明显大于纵桥向;车轮荷载作用下,正交异性桥面板应力分析时,荷载位置对纵横向应力峰值的影响很小,并且横桥向应力起控制作用,峰值均出现在U肋与顶板交接处。

Mechanical characteristics of decks for double-deck steel truss girder was studied taking the Shanghai Minpu Bridge as the engineering background,which has the longest span of double-decks cable-stayed bridge until now.The finite element model of the bridge with fine beam and shell elements was discussed in details.The axile force in web members between decks and the stress distribution of the decks were investigated.Fine finite element model of decks with U-rib between the longitudinal and the cross beams was established to analyze the stress distribution of decks and U-rib,under action of vehicles load.Results show that the transversal stress of the bridge deck is larger than the longitudinal stress at both decks.The nonuniformity of the transversal stress distribution is much more significant than that of the longitudinal stress distribution on the decks.The location of the wheel load has little effect on the peak transversal and longitudinal stresses of orthotropic deck.The transversal stress plays an important role in the stress distribution,with the peak stress located at the intersection of the U-ribs and the top deck.